| Title | Oxidative stress response of Deinococcus geothermalis via a cystine importer |
|---|---|
| Author | Minwook Kim1, Sunwook Jeong2, Sangyong Lim2, Jeonggu Sim3, Ho-Gun Rhie1, and Sung-Jae Lee1,4* |
| Address | 1Department of Biology and Kyung Hee University, Seoul 02447, Republic of Korea, 2Division of Biotechnology, Korea Atomic Energy Research Institute, Jeongeup 56212, Republic of Korea, 3Department of Visual Optics, Baekseok University, Cheonan 31065, Republic of Korea, 4Department of Life and Nanopharmaceutical Sciences, Kyung Hee University, Seoul 02447, Republic of Korea |
| Bibliography | Journal of Microbiology, 55(2),137-146, 2017, |
| DOI | 10.1007/s12275-017-6382-y |
| Key Words | Deinococcus geothermalis, oxidative-stress response, H2O2 scavenger, cystine importer, anti-oxidation |
| Abstract | A cystine-dependent anti-oxidative stress response is characterized in Deinococcus geothermalis for the first time. Nevertheless, the same transcriptional directed Δdgeo_1985F mutant strain was revealed to have an identical phenotype to the wild-type strain, while the reverse transcriptional directed Δdgeo_1985R mutant strain was more resistant to oxidative stress at a certain concentration of H2O2 than the wild-type strain. The wild-type and mutant strains expressed equal levels of superoxide dismutase and catalase under H2O2-induced stress. Although the expression levels of the general DNAdamage response-related genes recA, pprA, ddrA, and ddrB were up-regulated by more than five-fold in the wild-type strain relative to the Δdgeo_1985R mutant strain, the mutant strain had a higher survival rate than the wild-type under H2O2 stress. The Δdgeo_1985R mutant strain highly expressed a cystine-transporter gene (dgeo_1986), at levels 150-fold higher than the wild-type strain, leading to the conclusion that this cystine transporter might be involved in the defensive response to H2O2 stress. In this study, the cystine transporter was identified and characterized through membrane protein expression analysis, a cystine-binding assay, and assays of intracellular H2O2, cysteine, and thiol levels. The genedisrupted mutant strain of the cystine importer revealed high sensitivity to H2O2 and less absorbed cystine, resulting in low concentrations of total thiol. Thus, the absorbed cystine via this cystine-specific importer may be converted into cysteine, which acts as a primitive defense substrate that non-enzymatically scavenges oxidative stress agents in D. geothermalis. |